He was a very powerful Congress leader who was known to have turned down high-ranking cabinet positions multiple times. He was once offered the Defense Cabinet Minister position by Mrs. Indira Gandhi and he refused to take it. He, much like his mentor Thiru Kamajar, was also known as the "King Maker."

Moopanar came very close to becoming the Prime Minister of India in 1997 when Harkishan Singh Surjeet and Jyoti Basu asked him to lead the United Front government supported by Congress. He however declined the offer like his mentor K Kamaraj.

Thiru.G.K. Moopanar had friends and associates cutting across party lines, and was also a close confidant of Prime Ministers Indira Gandhi and Rajiv Gandhi, moreover he was instrumental in making Rajiv Gandhi as the Prime Minister in 1984 after the death of Indira Gandhi .He was a patron of Arts and Music especially Carnatic music.

After the demise of Moopanar, under the new leadership of his son G K Vasan, the TMC merged back with the Congress led by Sonia Gandhi.